A new, low-T-g siloxane thermoplastic elastomer with a functionalizable backbone was synthesized via sequential anionic polymerization and coupling, and its utility as a platform to produce functional elastomers was demonstrated by the attachment of a photoresponsive liquid crystal to produce a rapid, room temperature photoactuator. Polystyrene was used as a hard glassy end block, and poly(vinylmethylsiloxane) served as the soft middle segment in a polystyrene-b-poly(vinylmethylsiloxane)-b-polystyrene ABA triblock copolymer. The vinyl side chain was used to attach a side on oriented mesogen to the siloxane backbone, and the resulting liquid crystal triblock copolymer was characterized with reversible photocontraction tests, where it was shown to be both elastomeric and rapidly photoresponsive at room temperature. Rather than simply undergoing a bending mechanism, an oriented thin cast film of the elastomer was observed to contract reversibly at a tensile strain of 3.3% against 253 kPa of applied stress in similar to 5.9 s. This strategy to produce functional liquid crystal elastomers is based on the formation of spherical block copolymers with a low temperature T-g for the soft domain, in contrast to cross linked elastomers. Because the approach is simple, robust, and applicable to a wide variety of functional moieties, the resulting materials are thermoplastics that can be processed to achieve preferential orientation using standard methods, thus enhancing the capability to produce and utilize functional actuators.